Method and device for performing cooling- or cryo-therapies for, e.g., angioplasty with reduced restenosis or pulmonary vein cell necrosis to inhibit atrial fibrillation employing microporous balloon

ABSTRACT

An enhanced method and device are provided to inhibit or reduce restenosis following angioplasty or stent placement. A porous balloon-tipped catheter is disposed in the area treated or opened through balloon angioplasty immediately following angioplasty. The balloon, which can have a dual balloon structure, may be delivered through a guiding catheter and over a guidewire already in place. A fluid such as a perfluorocarbon flows into the balloon to freeze the tissue adjacent the balloon, this cooling being associated with reduction of restenosis. A similar catheter may be used to reduce atrial fibrillation by inserting and inflating the porous balloon such that an exterior surface of the balloon, as well as a portion of the cold working fluid, from the microporosity contacts at least a partial circumference of the portion of the pulmonary vein adjacent the left atrium.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. pat. application Ser. No.09/932,402 filed on Aug. 17, 2001, now U.S. Pat. No. 6,685,732, entitled“Method And Device For Performing Cooling- Or Cryo-Therapies For, E.G.,Angioplasty With Reduced Restenosis or Pulmonaiy Vein Cell Necrosis ToInhibit Afrial Fibrillation Employing Microporous Balloon”, which is acontinuation-in-put of U.S. patent application No. 09087,599 filed Mar.21, 2001, now U.S. Pat. No. 6,602,276, entitled “Method and Device forPerforming Cooling-or Ciyo-Therapies for, e.g., Angioplasty with ReducedRestenosis or Pulmonary Vein Cell Necrosis to Inhibit AfrialFibrillation” which is a continuation-in-part of U.S. patent applicationNo.09/516,319, now abandoned, filed Mar. 1, 2000, entitled “Method andDevice for Performing Cooling- or Cryo-Therapies for, e.g., Angioplastywith Reduced Restenosis or Pulmonary Vein Cell Necrosis to InhibitAfrial Fibrillation” which is a continuation-in-part of U.S. patentapplication Ser. No.09/052,545, filed Mar. 31, 1998, now U.S. Pat. No.6,231,595, entitled “Circulating Fluid Hypothermia Method and Apparatus”and U.S. patent application Ser. No. 09/215,038, filed Dec. 16, 1998,now U.S. Pat. No. 6,261,312, entitled “Inflatable Catheter for SelectiveOrgan Heating and Cooling and Method of Using the Same”.

CROSS-REFERENCE TO MICROFICHE APPENDIX

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BACKGROUND OF THE INVENTION

Balloon angioplasty, or the technology of reshaping of a blood vesselfor the purpose of establishing vessel patency using a balloon tippedcatheter, has been known since the late 1970's. The procedure involvesthe use of a balloon catheter that is guided by means of a guidewirethrough a guiding catheter to the target lesion or vessel blockage. Theballoon typically is equipped with one or more marker bands that allowthe interventionalist to visualize the position of the balloon inreference to the lesion with the aid of fluoroscopy. Once in place,i.e., centered with the lesion, the balloon is inflated with abiocompatible fluid, and pressurized to the appropriate pressure toallow the vessel to open.

Typical procedures are completed with balloon inflation pressuresbetween 8 and 12 atmospheres. A percentage of lesions, typically heavilycalcified lesions, require much higher balloon inflation pressures,e.g., upward of 20 atmospheres. At times, the balloon inflationprocedure is repeated several times before the lesion or blockage willyield. The placement of stents after angioplasty has become popular asit reduces the rate of restenosis.

Restenosis refers to the renarrowing of the vascular lumen followingvascular intervention such as a balloon angioplasty procedure or stentinsertion. Restenosis is clinically defined as a greater than 50% lossof initial lumen diameter. The mechanism or root causes of restenosisare still not fully understood. The causes are multifactorial, and arepartly the result of the injury caused by the balloon angioplastyprocedure and stent placement. With the advent of stents, restenosisrates have dropped from over 30% to 10-20%. Recently, the use andeffectiveness of low-dose radiation administered intravascularlyfollowing angioplasty is being evaluated as a method to alter the DNA orRNA of an affected vessel's cells in the hope of reducing cellproliferation.

Another cardiological malady is atrial fibrillation. Atrial fibrillationrefers to very rapid irregular contractions of the atria of the heartresulting in a lack of synchronization between the heartbeat and thepulse. The irregular contractions are due to irregular electricalactivity that originates in the area of the pulmonary veins. A proposeddevice, currently under development, for treating atrial fibrillation isa balloon filled with saline that can be ultrasonically agitated andheated. This device is inserted in the femoral vein and snaked into theright atrium. The device is then poked through the interatrial septumand into the left atrium, where it is then angled into the volumeadjoining the suspect pulmonary vein with the left atrium.

Research in atrial fibrillation indicates that substantially completecircumferential necrosis is required for a therapeutic benefit. Theabove technique is disadvantageous in that circumferential portions ofthe tissue, desired to be necrosed, are not in fact affected. Othertechniques, including RF ablation, are similarly inefficient. Moreover,these techniques leave the necrosed portions with jagged edges, i.e.,there is poor demarcation between the healthy and the necrosed tissue.These edges can then cause electrical short circuits, and associatedelectrical irregularities, due to the high electric fields associatedwith jagged edges of a conductive medium.

The above technique is also disadvantageous in that heating is employed.Heating is associated with several problems, including increasedcoagulum and thrombus formation, leading to emboli. Heating alsostimulates stenosis of the vein. Finally, since tissues can only safelybe heated to temperatures of less than or about 75° C.-85° C. due tocharring and tissue rupture secondary to steam formation. The thermalgradient thus induced is fairly minimal, leading to a limited heattransfer. Moreover, since heating causes tissues to become less adherentto the adjacent heat transfer element, the tissue contact with the heattransfer element is also reduced, further decreasing the heat transfer.

Another disadvantage that may arise during either cooling or heatingresults from the imperfections of the surface of the tissue at oradjacent to the point of contact with the cryoballoon (in the case ofcooling). In particular, surface features of the tissue may affect thelocal geometry such that portions of the balloon attain a bettercontact, and thus a better conductive heat transfer, with the tissue.Such portions may be more likely to achieve cell necrosis than otherportions. As noted above, incomplete circumferential necrosis is oftendeleterious in treating atrial fibrillation and may well be furtherdeleterious due to the necessity of future treatments. Accordingly, amethod and device to achieve better conductive heat transfer betweentissue to be ablated and an ablation balloon is needed.

SUMMARY OF THE INVENTION

The present invention provides an enhanced method and device to inhibitor reduce the rate of restenosis following angioplasty or stentplacement. The invention is similar to placing an ice pack on a sore oroverstrained muscle for a period of time to minimize or inhibit thebiochemical events responsible for an associated inflammatory response.An embodiment of the invention generally involves placing aballoon-tipped catheter in the area treated or opened through balloonangioplasty immediately following angioplasty. A so-called “cryoplasty”balloon, which can have a dual balloon structure, may be deliveredthrough a guiding catheter and over a guidewire already in place from aballoon angioplasty. The dual balloon structure has benefits describedbelow and also allows for a more robust design. The balloon is porous sothat an amount of ablation fluid is delivered to the tissue at theablation site.

The balloon may be centered in the recently opened vessel with the aidof radio opaque marker bands, indicating the “working length” of theballoon. In choosing a working length, it is important to note thattypical lesions may have a size on the order of 2-3 cm. In the dualballoon design, biocompatible heat transfer fluid, which may containcontrast media, may be infused through the space between the dualballoons. While this fluid does not circulate in this embodiment, onceit is chilled or even frozen by thermal contact with a cooling fluid, itwill stay sufficiently cold for therapeutic purposes. Subsequently, abiocompatible cooling fluid with a temperature between about, e.g., −40°C. and −60° C., may be injected into the interior of the inner balloon,and circulated through a supply lumen and a return lumen. The fluidexits the supply lumen through a skive in the lumen, and returns to therefrigeration unit via another skive and the return lumen.

The biocompatible cooling fluid chills the biocompatible heat transferfluid between the dual balloons to a therapeutic temperature betweenabout, e.g., 0° C. and −50° C. The chilled heat transfer fluid betweenthe dual balloons transfers thermal energy through the balloon wall andinto the adjacent intimal vascular tissue for the appropriatetherapeutic length of time.

To aid in conduction, a small portion of the chilled heat transfer fluidbetween the dual balloons may contact the adjacent intimal vasculartissue for the appropriate therapeutic length of time due to theporosity or microporosity of the outer balloon.

Upon completion of the therapy, the circulation of the biocompatiblecooling fluid is stopped, and the remaining heat transfer fluid betweenthe dual balloons withdrawn through the annular space. Both balloons maybe collapsed by means of causing a soft vacuum in the lumens. Oncecollapsed, the cryoplasty catheter may be withdrawn from the treatedsite and patient through the guiding catheter.

In more detail, in one aspect, the invention is directed to a device totreat tissue, including an outer tube, an inner tube disposed at leastpartially within the outer tube, and a dual balloon including an innerballoon and an outer balloon, the inner balloon coupled to the innertube at a proximal and at a distal end, the outer balloon coupled to theinner tube at a distal end and to the outer tube at a proximal end. Afirst interior volume is defined between the outer balloon and the innerballoon in fluid communication with an inlet in the volume between theouter tube and the inner tube. The outer balloon is porous so that anamount of ablation fluid may be delivered to the ablation site.

Variations of the invention may include one or more of the following.The inner tube may further define a guidewire lumen, a supply lumen, anda return lumen. The supply lumen may define a hole or skive such that afluid flowing in the supply lumen may be caused to flow into a volumedefined by the inner balloon, and the return lumen may define a hole orskive such that a fluid flowing in a volume defined by the inner balloonmay be caused to flow into the return lumen. The guidewire lumen mayextend from a proximal end of the inner tube to a distal end of theinner tube. The device may further comprise at least two radiallyextending tabs disposed around a circumference of the inner tube tosubstantially center the inner tube within the dual balloon. The devicemay further comprise at least one marker band disposed on the inner tubeto locate a working region of the device at a desired location. Thedevice may further comprise a source of chilled fluid having a supplytube and a return tube, the supply tube coupled in fluid communicationto the supply lumen and the return tube coupled in fluid communicationto the return lumen. A source of fluid may also be included, the sourceof fluid coupled in fluid communication to a volume between the innerballoon and the outer balloon. The fluid may be a perfluorocarbon suchas Galden fluid. The fluid may also include contrast media. The size ofthe pores of the outer balloon may be in the micron range, so long asthe pores do not prevent the balloon from achieving a pressure of about1 to 2 atmospheres. The pores may be disposed in one of a variety ofshapes, including a band, a helix, and so on. The use of just a singlepore may be employed as well to minimize fluid loss while still allowingsome conduction enhancement.

In another aspect, the invention is directed to a method of reducingrestenosis after angioplasty in a blood vessel. The method includesinserting a catheter into a blood vessel, the catheter having a balloon.The balloon is then inflated with a perfluorocarbon such that anexterior surface of the balloon is in contact with at least a partialinner perimeter of the blood vessel, the perfluorocarbon having atemperature in the range of about −10° C. to −50° C. The balloon isporous so that an amount of ablation fluid is delivered to the ablationsite.

Variations of the method may include one or more of the following. Themethod may include disposing the catheter at a desired location using atleast one radio opaque marker band. The method may include flowing theperfluorocarbon into the balloon using a supply lumen and exhausting theremaining perfluorocarbon from the balloon using a return lumen. Theballoon may be a dual balloon, and the method may further includeproviding a heat transfer fluid in the volume between the dual balloons.The heat transfer fluid may include a contrast media fluid. The methodmay include disposing the catheter such that at least a portion of theballoon is in a coronary artery or in a carotid artery. The size of thepores of the balloon may be in the micron range, so long as the poresare not so large or multitudinous so as to prevent the balloon fromachieving a pressure of at least about 1 to 2 atmospheres. The pores maybe disposed in one of the variety of shapes disclosed above, includingjust a single pore.

In yet another aspect, the invention is directed to a method of reducingatrial fibrillation. The method includes inserting a catheter at leastpartially into the heart, the catheter having a balloon, a portion ofthe balloon located in the left atrium and a portion of the balloonlocated in a pulmonary vein. The balloon is porous so that an amount ofablation fluid is delivered to the ablation site. The balloon isinflated with a perfluorocarbon such that an exterior surface of theballoon, as well as a small portion of the ablation fluid, is in contactwith at least a partial circumference of the portion of the pulmonaryvein adjacent the left atrium, the perfluorocarbon having a temperaturein the range of about −10° C. to −50° C.

Variations of the method may include one or more of the following. Theballoon may have a working region having a length of between about 5 mmand 10 mm. The method may further include inserting a wire having aneedle point from the femoral vein into the right atrium and forming ahole using the needle point in the interatrial septum between the rightatrium and the left atrium. A guide catheter may then be inserted intothe right atrium. A guide wire may further be inserted through the guidecatheter into the right atrium and further into a pulmonary vein. Thecatheter may then be disposed over the guidewire into a volume definedby the joint of the right atrium and the pulmonary vein. The size of thepores of the outer balloon may be in the micron range, so long as thepores do not prevent the balloon from achieving a pressure of about 1 to2 atmospheres. The pores may be disposed in one of a variety of shapes,including a band, a helix, and so on. The use of just a single pore maybe employed as well to minimize fluid loss while still allowing someconduction enhancement.

Advantages of the invention may include one or more of the following.The invention inhibits or reduces the rate of restenosis following aballoon angioplasty or any other type of vascular intervention. At leastthe following portions of the vascular anatomy can benefit from such aprocedure: the abdominal aorta (following a stent or graft placement),the coronary arteries (following PTCA or rotational artherectomy), thecarotid arteries (following an angioplasty or stent placement), as wellas the larger peripheral arteries.

When the invention is used to treat atrial fibrillation, the followingadvantages inure. The cooled tissue is adherent to the heat transferelement and/or to the ablative fluid, increasing the heat transfereffected. Since very cold temperatures may be employed, the temperaturegradient can be quite large, increasing the heat transfer rate. Theablative fluid that passes from the balloon to the tissue may assist theheat transfer conduction and the ensuing cell necrosis.

In both embodiments, heat transfer does not occur primarily or at all byvaporization of a liquid, thus eliminating a potential cause of bubblesin the body. Nor does cooling occur primarily or at all by a pressurechange across a restriction or orifice, this simplifying the structureof the device. Thrombus formation and charring, associated with priortechniques, are minimized or eliminated.

Additional advantages will be apparent from the description thatfollows, including the drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a side schematic view of a catheter according to a firstembodiment of the invention.

FIG. 1B shows a cross-sectional view of the catheter of FIG. 1A, asindicated by lines 1B-1B in FIG. 1A.

FIG. 1C shows an alternate cross-sectional view of the catheter of FIG.1A, as indicated by lines 1B-1B in FIG. 1A.

FIG. 2A shows a side schematic view of a catheter according to a secondembodiment of the invention.

FIG. 2B shows a cross-sectional view of the catheter of FIG. 2A, asindicated by lines 2B-2B in FIG. 2A.

FIG. 3 shows a schematic view of a catheter in use according to a thirdembodiment of the invention.

FIG. 4 shows a cross-sectional view of the catheter of FIG. 3.

FIG. 5 shows an alternative cross-sectional view of the catheter of FIG.3.

FIG. 6 shows an alternative cross-sectional view of the catheter of FIG.3.

FIG. 7 shows a schematic view of the warm balloon of the catheter ofFIG. 3.

FIG. 8 shows a side schematic view of a catheter according to a fourthembodiment of the invention, this embodiment employing a porous balloon.

FIG. 9 shows a side schematic view of a catheter according to a fifthembodiment of the invention, this embodiment employing a porous balloon.

DETAILED DESCRIPTION

Referring to FIG. 1A, a catheter 100 is shown according to a firstembodiment of the invention. The catheter 100 has a proximal end 130 anda distal end 114. Of course, this figure is not necessarily to scale andin general use the proximal end 130 is far upstream of the featuresshown in FIG. 1A.

The catheter 100 may be used within a guide catheter 102, and generallyincludes an outer tube 103, a dual balloon 134, and an inner tube 122.These parts will be discussed in turn.

The guide catheter 102 provides a tool to dispose the catheter 100adjacent the desired location for, e.g., angioplasty or reduction ofatrial fibrillation. Typical guide catheter diameters may be about 6French to 9 French, and the same may be made of polyether blockamide,polyamides, polyurethanes, and other similar materials. The distal endof the guide catheter is generally adjacent the proximal end of the dualballoon 134, and further is generally adjacent the distal end of theouter tube 103.

The ability to place the guide catheter is a significant factor in thesize of the device. For example, to perform angioplasty in the carotidarteries, which have an inner diameter of about 4 to 6 mm, a suitablysized guide catheter must be used. This restricts the size of thecatheter 100 that may be disposed within the guide catheter. A typicaldiameter of the catheter 100 may then be about 7 French or less or about65 to 91 mils. In a second embodiment described below, a catheter foruse in the coronary arteries is described. Of course, which catheter isused in which artery is a matter to be determined by the physician,taking into account such factors as the size of the individual patient'saffected arteries, etc.

The outer tube 103 houses the catheter 100 while the latter traversesthe length of the guide catheter 102. The outer tube 103 may have adiameter of about 0.4 French to 7 French, and the same may be made ofpolyether blockamide, poly-butylene terephtalate, polyurethane,polyamide, polyacetal polysulfone, polyethylene, ethylenetetrafluoroethylene, and other similar materials.

The distal end of the outer tube 103 adjoins the proximal end of thedual balloon 134. The outer tube 103 provides a convenient location formounting a proximal end of an outer balloon 104 within the dual balloon134, and further may provide an inlet 128 for providing a fluid such asa liquid to a first interior volume 106 between the dual balloons. Insome cases, an inlet 128 per se may not be necessary: the fluid, whichmay also be a sub-atmospheric level of gas or air, may be providedduring manufacture in the first interior volume 106. In this case, theproximal and distal ends of the first interior volume may be sealedduring manufacture. The inlet 128 may be at least partially defined bythe annular volume between the interior of the outer tube 103 and theexterior of the inner tube 122.

The dual balloon 134 includes an outer balloon 104 and an inner balloon108. Between the two is the first interior volume 106. The outer balloon104 may be inflated by inflating the interior volume 106. The innerballoon 108 has a second interior volume 110 associated with the same.The inner balloon 108 may be inflated by inflating the second interiorvolume 110.

To avoid the occurrence of bubbles in the bloodstream, both the innerballoon 108 and the outer balloon 104 may be inflated usingbiocompatible liquids, such as Galden® fluid, perfluorocarbon-basedliquids, or various contrast agents. There is no need that the fluidinflating one of the interior volumes be the same fluid as thatinflating the other. Additional details on these fluids are describedbelow.

In the case of the first interior volume 106, this fluid may be, e.g.,stationary or static: in other words, it need not be circulated. In thecase of the second interior volume 110, this fluid would in general becirculated by an external chiller (not shown). The chiller may be, e.g.,a gear pump, peristaltic pump, etc. It may be preferable to use a gearpump over a peristaltic pump as the attainable pressure of the former isgenerally greater than that of the latter. Moreover, gear pumps have theadvantageous property of being linear, i.e., their output varies indirection proportion with their revolutions per minute. Two types ofgear pumps which may be employed include radial spur gear pumps andhelical tooth gear pumps. Of these, the helical tooth gear pump may bemore preferable as the same has been associated with higher pressuresand a more constant output. The ability to achieve high pressures may beimportant as the cooling fluid is required to pass through a fairlynarrow, e.g., five to seven French, catheter at a certain rate. For thesame reason, the viscosity of the fluid, at the low temperatures, shouldbe appropriately low. In this way, e.g., the flow may be increased. Forexample, an appropriate type of fluid may be Galden® fluid, and inparticular Galden® fluid item number “HT-55”, available from AusimontInc. of Thorofare, N.J. At −55° C., this fluid has a viscosity of 2.1centiStokes. At −70° C., this fluid has a viscosity of 3.8 centiStokes.It is believed that fluids with such viscosities at these temperatureswould be appropriate for use.

The so-called “cones” of the balloons 108 and 104, indicated generallyby reference numeral 132, may be made somewhat thicker than theremainder of the balloon sections. In this way, the heat transferefficiency in these sections is significantly less than over theremainder of the balloon sections, this “remainder” effectively defininga “working region” of the balloon. In this way, the cooling or“cryoplasty” may be efficiently localized to the affected area ratherthan spread over the length of the balloon.

The inner tube 122 is disposed within the interior of the dual balloon134 and within the interior of the guide catheter 102. The inner tube122 includes a supply lumen 120, a return lumen 118, and a guidewirelumen 116. The guidewire lumen 116 may have sizes of, e.g., 17 or 21mils inner diameter, in order to accommodate current standard sizedguidewires, such as those having an outer diameter of 14 mils. Thisstructure may be preferable, as the pressure drop encountered may besubstantially less. In use, the supply lumen 120 may be used to supply acirculating liquid to the second interior volume 110. The return lumen118 may be used to exhaust the circulating liquid from the secondinterior volume to the external chiller. As may be seen from FIG. 1A,both lumens 118 and 120 may terminate prior to the distal end 114 of thecatheter 100. The lumen arrangement may be seen more clearly in FIG. 1B.FIG. 1C shows an alternate such arrangement, and one that may provide aneven better design for minimal pressure drop. In this design, lumens118′ and 120′ are asymmetric about guidewire lumen 116′.

A set of radio opaque marker bands 112 may be disposed on the inner tube122 at locations substantially adjacent the cones 132 to define acentral portion of the “working region” of the balloons 104 and 108.This working region is where the “cryoplasty” procedures described belowmay substantially occur.

As noted above, the proximal portion of the outer balloon 104 is mountedon the outer tube 103 at its distal end. The distal end of the outerballoon 104 is secured to the distal end of the catheter 100 and alongthe inner tube 122. In contrast, both the proximal and distal ends ofthe inner balloon 108 may be secured to the inner tube 122 to create asealed second interior volume 110.

At least two skives 124 and 126 may be defined by the inner tube 122 andemployed to allow the working fluid to exit into the second interiorvolume 110 and to exhaust the same from the second interior volume 10.As shown in the figure, the skive 124 is in fluid communication with thelumen 120 and the skive 126 is in fluid communication with the lumen118. Here, “fluid communication” refers to a relationship between twovessels where a fluid pressure may cause a net amount of fluid to flowfrom one vessel to the other.

The skives may be formed by known techniques. A suitable size for theskives may be from about 50 mils to 125 mils.

A plurality of optional tabs 119 may be employed to roughly orsubstantially center the inner tube 122 within the catheter 100. Thesetabs may have the shape shown, the shape of rectangular or triangularsolids, or other such shapes so long as the flow of working fluid is notunduly impeded. In this specification, the phrase “the flow of workingfluid is not unduly impeded” is essentially equated to the phrase“substantially center”. The tabs 119 may be made of polyetherblockamide, poly-butylene terephtalate, polyurethane, polyamide,polyacetal polysulfone, polyethylene, ethylene tetrafluoroethylene, andother similar materials, and may have general dimensions of from about 3mils to 10 mils in height, and by about 10 mils to 20 mils in width.

In a method of use, the guide catheter 102 may be inserted into anaffected artery or vein such that the distal tip of the guide catheteris just proximal to an affected area such as a calcified area or lesion.Of course, it is noted that typical lesions do not occur in the venoussystem, but only in the arterial.

This step provides a coarse estimate of proper positioning, and mayinclude the use of fluoroscopy. The guide catheter may be placed using aguide wire (not shown). Both the guide catheter and guide wire mayalready be in place as it may be presumed a balloon angioplasty or stentplacement has previously been performed.

The catheter 100 may then be inserted over the guide wire via the lumen116 and through the guide catheter 102. In general, both a guide wireand a guide catheter are not strictly necessary—one or the other mayoften suffice. During insertion, the dual balloon 134 may be uninflatedto maintain a minimum profile. In fact, a slight vacuum may be drawn tofurther decrease the size of the dual balloon 134 so long as thestructural integrity of the dual balloon 134 is not thereby compromised.

When the catheter 100 is distal of the distal tip of the guide catheter102, a fine positioning step may occur by way of the radio opaque markerbands 112. Using fluoroscopy, the location of the radio opaque markerbands 112 can be identified in relation to the location of the lesion.In particular, the catheter may be advantageously placed at the locationof the lesion and further such that the lesion is between the two markerbands. In this way, the working region of the balloon 134 willsubstantially overlap the affected area, i.e., the area of the lesion.

Once placed, a biocompatible heat transfer fluid, which may also containcontrast media, may be infused into the first interior volume 106through the inlet 128. While the use of contrast media is not required,its use may allow early detection of a break in the balloon 104 becausethe contrast media may be seen via fluoroscopy to flow throughout thepatient's vasculature. Subsequently a biocompatible cooling fluid may becirculated through the supply lumen 120 and the return lumen 118. Beforeor during the procedure, the temperature of the biocompatible coolingfluid may be lowered to a therapeutic temperature, e.g., between −40° C.and −60° C., although the exact temperature required depends on thenature of the affected area. The fluid exits the supply lumen 120through the skive 124 and returns to the chiller through the skive 126and via the return lumen 118. It is understood that the respective skivefunctions may also be reversed without departing from the scope of theinvention.

The biocompatible cooling fluid in the second interior volume 110 chillsthe biocompatible heat transfer fluid within the first interior volume106 to a therapeutic temperature of, e.g., between about −25° C. and−50° C. The chilled heat transfer fluid transfers thermal energy throughthe wall of the balloon 104 and into the adjacent intimal vasculartissue for an appropriate therapeutic length of time. This time may be,e.g., about ½ to 4 minutes.

Upon completion of the therapy, the circulation of the biocompatiblecooling fluid may cease. The heat transfer fluid within the firstinterior volume 106 may be withdrawn though the inlet 128. The balloons104 and 108 may be collapsed by pulling a soft vacuum through any or allof the lumens 124, 126, and 128. Following collapse, the catheter 100may be withdrawn from the treatment site and from the patient throughthe guide catheter 102.

To inhibit restenosis, the following therapeutic guidelines may besuggested:

Minimum Average Maximum Temperature −20° C. −55° C. −110° C. of heattransfer fluid Temperature    0° C. to −10° C. −20° C. to  −50° C. toachieved at −30° C. −100° C. intimal wall Depth of 10ths of mm 1 mm 3 mmpenetration of intema/media Length of 30 seconds 1-2 min 4-5 min timefluid is circulating

Substantially the same catheter may be used to treat atrialfibrillation. In this method, the catheter is inflated as above once itis in location. The location chosen for treatment of atrial fibrillationis such that the working region spans a portion of the left atrium and aportion of the affected pulmonary vein. Thus, in this embodiment, theworking region of the catheter may have a length of about 5 mm to 30 mm.The affected pulmonary vein, of the four possible pulmonary veins, whichenter the left atrium, may be determined by electrophysiology studies.

To maneuver the catheter into this location, a catheter with a needlepoint may first be inserted at the femoral vein and routed up to theright atrium. The needle of the catheter may then be poked through theinteratrial septum and into the left atrium. The catheter may then beremoved if desired and a guide catheter disposed in the same location. Aguide wire may be used through the guide catheter and may be maneuveredat least partially into the pulmonary vein. Finally, a catheter such asthe catheter 100 may be placed in the volume defining the intersectionof the pulmonary vein and the left atrium.

A method of use similar to that disclosed above is then employed to coolat least a portion of, and preferably all of, the circumferentialtissue. The coldness of the balloon assists in the adherence of thecircumferential tissue to the balloon, this feature serving to increasethe overall heat transfer rate.

The catheter 100 above may be particularly useful for procedures in thecarotid arteries by virtue of its size. For use in the coronaryarteries, which are typically much smaller than the carotid artery, aneven smaller catheter may be desired. For example, one with an outerdiameter less than 5 French may be desired.

Referring to FIG. 2A, a catheter 200 is shown according to a secondembodiment of the invention. This embodiment may be particularly usefulfor use in the coronary arteries because the dimensions of the catheter200 may be considerably smaller than the dimensions of the catheter 100.However, in several ways the catheter 200 is similar to theabove-described catheter 100. In particular, the catheter 200 has aproximal end 230 and a distal end 214 and may be used within a guidecatheter 202. The catheter 200 includes an outer tube 203, a dualballoon 234, and an inner tube 222.

The ability to place the guide catheter is a significant factor in thesize of the device. For example, to perform angioplasty in the coronaryarteries, which have an inner diameter of about 1½ to 4½ mm, a suitablysized guide catheter may be used. This then restricts the size of thecatheter 200 which may be disposed within the guide catheter. A typicaldiameter of the catheter 200 may then be about 3 French or less or about35-39 mils. The same may be placed in the femoral artery in order to beable to track to the coronary arteries in a known manner.

Analogous to these features in the catheter 100, the outer tube 203houses the catheter 200 and may have an outside diameter of about 5French to 7 French, and the same may be made of similar materials. Thedistal end of the outer tube 203 adjoins the proximal end of the dualballoon 234. The outer tube 203 provides a mounting location for anouter balloon 204, and further provides an inlet 228 for providing afluid such as a liquid to a first interior volume 206 between the dualballoons. As noted in connection with catheter 100, an inlet 228 per semay not be necessary: the fluid, which may also be a sub-atmosphericlevel of air, may be provided in the first interior volume 206. Also asabove, the proximal and distal ends of the volume may be sealed duringmanufacture. The inlet 228 may be at least partially defined by theannular volume between the interior of the outer tube 203 and theexterior of the inner tube 222.

The dual balloon 234 includes an outer balloon 204 and an inner balloon208. These balloons are basically similar to balloons 104 and 108described above, but may be made even smaller for use in the smallercoronary arteries.

The same types of fluids may be used as in the catheter 100.

The inner tube 222 is disposed within the interior of the dual balloon234 and within the interior of the guide catheter 202. The inner tube222 includes a supply lumen 220 and a return lumen 218.

A set of radio opaque marker bands 212 may be disposed on the inner tube222 for the same reasons disclosed above in connection with the markerbands 112.

As noted above, the proximal portion of the outer balloon 204 is mountedon the outer tube 203 at its distal end. The distal end of the outerballoon 204 is secured to the distal end of the catheter 200 and alongthe inner tube 222. In contrast, both the proximal and distal ends ofthe inner balloon 208 may be secured to the inner tube 222 to create asealed second interior volume 210.

At least two skives 224 and 226 may be defined by the inner tube 222 andemployed to allow the working fluid to exit into the second interiorvolume 210 and to exhaust the same from the second interior volume 210.

A plurality of optional tabs 219 may be employed to roughly orsubstantially center the inner tube 222 within the catheter 200 as incatheter 100. These tabs may have the same general geometry and designas tabs 119. Of course, they may also be appropriately smaller toaccommodate the smaller dimensions of this coronary artery design.

The tabs 119 and 219 are particularly important in the catheters 100 and200, as contact by the inner tube of the outer tube may also beassociated with an undesired conductive heat transfer prior to theworking fluid reaching the working region, thereby deleteriouslyincreasing the temperature of the working fluid at the working region.

The method of use of the catheter 200 is generally the same as for thecatheter 100. Known techniques may be employed to place the catheter 200into an affected coronary artery. For the catheter 200, an externalguidewire may be used with appropriate attachments to the catheter.

Referring to FIG. 3, an alternative embodiment of a catheter 300 whichmay be employed in PV ablation is detailed. In this figure, a dualballoon system 301 is shown; however, the balloons are not one withinthe other as in FIG. 1. In this embodiment, a warm balloon 302 is distalof a cold balloon 304. Warm balloon 302 may be used to anchor the system301 against movements, which may be particularly useful within a beatingheart. Cold balloon 304 may then be employed to cryo-ablate acircumferential lesion at the point where a pulmonary vein 306 entersthe left atrium 308.

Within the cold balloon 304, a working fluid may be introduced via anoutlet port 308 and may be retrieved via an inlet port 310. Ports 308and 310 may be skived in known fashion into the catheter shaft lumenswhose design is exemplified below.

As noted above, the warm balloon 302 serves to anchor the system 301 inthe pulmonary vein and left atrium. The warm balloon 302 also serves tostop blood, which is traveling in the direction indicated by arrow 312,from freezing upon contact with the cold balloon 304. In this way, thewarm balloon 302 acts as an insulator to cold balloon 304.

As the warm balloon 302 does not require convective heat transfer via acirculating working fluid, it may be served by only one skived port, orby two ports, such as an inlet port 314 and an outlet port 316, as shownin FIG. 3. In some embodiments, a separate lumen or lumens may be usedto fill the warm balloon. In an alternative embodiment, a valvemechanism may be used to fill the warm balloon using fluid from the coldballoon. In the case where only one port is used to fill the warmballoon, draining the same requires a slight vacuum or negative pressureto be placed on the lumen servicing the inlet/outlet port. A benefit tothe two lumen design is that the warm balloon may be inflated anddeflated in a more expeditious manner.

Typical pressures within the warm balloon may be about 1-2 atm (10-30psi), and thus maintains a fairly low pressure. An appropriate fluidwill be biocompatible, and may be Galden fluid, DSW, and so on. Typicalpressures within the cold balloon may be about 5-7 atm, for exampleabout 6 atm (e.g., at about 100 psi), and thus maintains a higherpressure. An appropriate fluid may be Galden fluid, e.g., HT-55, D5W,and so on. The volume of fluid required to fill the cold balloon mayvary, but may be about 4-8 cc. The cold balloon may be about 2 to 2½ cmlong, and have a diameter of 1 to 2½ cm.

In some embodiments, the warm balloon may be glued or otherwise attachedto the cold balloon. In the case where only one port is used to fill thewarm balloon, draining both balloons may simply entail closing eitherthe return lumen or the supply lumen, and drawing a vacuum on the other.In this way, both the cold and warm balloons may be evacuated. In anycase, a standard medical “indeflator” may be used to pressurize andde-pressurize the various lumens and balloons.

FIG. 4 shows an embodiment of the arrangement of lumens within thecatheter. In particular, supply and return lumens for the cold balloon304 are shown by lumens 318 and 320, respectively. Supply and returnlumens for the warm balloon 302 are shown by lumens 322 and 324,respectively, although as noted only one may be used as required by thedictates of the user. A guidewire lumen 326 is also shown. Analternative arrangement is shown in FIG. 5, where the correspondinglumens are shown by primes.

In the above lumen designs, the exterior blood is exposed to the coldsupply flow. Referring to FIG. 6, an alternative lumen design is shownin which the cold fluid supply lumen 328 is exposed to only the coldfluid return lumen 330. An insulation space 332 may also be employed. Inthis way, the heat flux from the exterior flow is minimized and the coldfluid may reach the cold balloon at a lower temperature. One drawback tosuch a system is that the operational pressure may be higher.

Referring back to FIG. 4, the overall catheter outer diameter may beabout 0.130″, e.g. about 10 French, including an insulation sleeve andguide discussed below. The catheter shaft 303 itself may be about 0.110″and may be made of, e.g., polyethylene (PE), and preferably acombination of a low density PE and a high density PE.

The inlet and outlet ports or inlet/outlet port of the warm balloon maybe skived from the lumens 322 and 324. Referring to FIG. 7, the warmballoon 302 itself may be made of a sleeve 332 of silicone tubing of,e.g., 35 durometer on the “D” scale, and held in place by two pieces ofPET heat shrink tubing 334. Alternative methods of securing the warmballoon during inflation may include metal bands or an adhesive.

Referring back to FIG. 3, marker bands 336 may be employed within eitheror both of the cold balloon and warm balloon to assist the physician isdisposing the same in an appropriate location. The marker bandstypically denote the working areas of the balloons, and may be made ofPt, Iridium, Au, etc.

In the ablation procedure, the working cold fluid may exit thecirculation system or chiller at, e.g., about −85° C. The circulationsystem or chiller may be, e.g., a two-stage heat exchanger. The fluidmay then enter the catheter at about −70° C. to about −75° C., and maystrike the balloon at about −55° C. to about −65° C. The overallprocedure may take less than a minute to circumferentially ablate thedesired tissue up to several minutes. Of course, these numbers are onlyexemplary and the same depend on the design of the system and fluidsused.

Mapping electrodes 338 may be employed at the distal end of the warmballoon. These mapping electrodes may each have a wire attached, thewires extending down, e.g., the supply and return lumens for the warmfluid or the cold fluid. The mapping electrodes 338 may be used todetect stray electrical fields to determine where ablation may be neededand/or whether the ablation procedure was successful. The mappingelectrodes may typically be about 2-3 mm apart from each other.

Construction of the warm balloon typically involves adhering the same tothe shaft 303 and skiving the inlet and outlet ports. In some instances,it may be desired to place a silicone sleeve 340 on the proximal and/ordistal ends of the warm and/or cold balloons. The silicone sleeve 340may then serve to further insulate the non-working sections of theballoons from blood that would otherwise potentially freeze during aprocedure. The silicone sleeve would typically be attached only at aportion of its length, such as that indicated by circle 342, so that thesame may slide along the balloon as the balloon is inflated. In additionto insulation effects, the silicone sleeve also serves to assist incollapsing the balloon during deflation.

The entire catheter shaft 303 may be surrounded by an insulationcatheter sleeve 344 (see FIG. 4). Sleeve 344 may have a thickness of,e.g., 0.01 inches, and may be made of a foamed extrusion, e.g., thatwith voids of air disposed within. The voids further assist theinsulating effect since their heat transfer is extremely low. A void topolymer ratio of, e.g., 20% to 30% may be particularly appropriate. Suchfoamed extrusions are available from, e.g., Applied Medical Resources inLaguna Niguel, Calif., or Extrusioneering, Inc., in Temecula, Calif.

To prevent damage to tissue other than where the ablation is to occur,such as at the insertion site near the femoral vein and around thepuncture point through the atrial septum, an insulation sleeve may beused as noted above.

Of course, in certain situations, the warm balloon may be omitted, andonly the therapeutic cold balloon used. In a particularly simple system,the therapeutic cold balloon may be employed as a single balloon systemwithout the use of tabs. Such a system may be particularly convenient tomanufacture and install.

In another embodiment, the invention may employ a porous or microporousballoon to enhance heat transfer between the working fluid and thetissue to be treated. Referring to FIG. 8, a catheter 400 is shownaccording to a first embodiment of the invention. The catheter 400 has aproximal end 430 and a distal end 414. The catheter 400 may be usedwithin a guide catheter 402, and generally includes an outer tube 403, adual balloon 434, and an inner tube 422. These parts will be discussedin turn.

The guide catheter 402 may be similar to that discussed above inconnection with FIG. 1.

The outer tube 403 houses the catheter 400 while the latter traversesthe length of the guide catheter 402. The outer tube 403 may have adiameter of about 4 French to 7 French, and the same may be made ofpolyether blockamide, poly-butylene terephtalate, polyurethane,polyamide, polyacetal polysulfone, polyethylene, ethylenetetrafluoroethylene, and other similar materials.

The distal end of the outer tube 403 adjoins the proximal end of thedual balloon 434. The outer tube 403 provides a convenient location formounting a proximal end of an outer balloon 404 within the dual balloon434, and further may provide an inlet 428 for providing a fluid such asa liquid to a first interior volume 406 between the dual balloons. Insome cases, an inlet 428 per se may not be necessary: the fluid, whichmay also be a sub-atmospheric level of gas or air, may be providedduring manufacture in the first interior volume 406. In this case, theproximal and distal ends of the first interior volume may be sealedduring manufacture. The pressure of inflation would then provide theforce necessary to cause the fluid within the first interior volume toat least partially “leak” to the tissue. The inlet 428 may be at leastpartially defined by the annular volume between the interior of theouter tube 403 and the exterior of the inner tube 422.

The dual balloon 434 includes an outer balloon 404 and an inner balloon408. Between the two is the first interior volume 406. The outer balloon404 may be inflated by inflating the interior volume 406. The innerballoon 408 has a second interior volume 410 associated with the same.The inner balloon 408 may be inflated by inflating the second interiorvolume 410.

To avoid the occurrence of bubbles in the bloodstream, both the innerballoon 408 and the outer balloon 404 may be inflated usingbiocompatible liquids, such as Galden® fluid, perfluorocarbon-basedliquids, or various contrast agents. There is no need that the fluidinflating one of the interior volumes be the same fluid as thatinflating the other. Additional details on these fluids were describedabove.

In the case of the first interior volume 406, this fluid may be, e.g.,stationary or static: in other words, it need not be circulated. In thecase of the second interior volume 410, this fluid would in general becirculated by an external chiller (not shown). The chiller may be, e.g.,a gear pump, peristaltic pump, etc. It may be preferable to use a gearpump over a peristaltic pump for the reasons described above.

The inner tube 422 is disposed within the interior of the dual balloon434 and within the interior of the guide catheter 402. The inner tube422 includes a supply lumen 420, a return lumen 418, and a guidewirelumen 416. The guidewire lumen 416 may have sizes of, e.g., 17 or 21mils inner diameter, in order to accommodate current standard sizedguidewires, such as those having an outer diameter of 14 mils. Thisstructure may be preferable as described above. The return lumen 418 maybe used to exhaust the circulating liquid from the second interiorvolume to the external chiller. As may be seen from FIG. 8, both lumens418 and 420 may terminate prior to the distal end 414 of the catheter400. The lumen arrangement may be similar to that of FIG. 1B or 1C.

A set of radio opaque marker bands 412 may be disposed on the inner tube422 at locations substantially adjacent the cones 432 to define acentral portion of the “working region” of the balloons 404 and 408.

As noted above, the proximal portion of the outer balloon 404 is mountedon the outer tube 403 at its distal end. The distal end of the outerballoon 404 is secured to the distal end of the catheter 400 and alongthe inner tube 422. In contrast, both the proximal and distal ends ofthe inner balloon 408 may be secured to the inner tube 422 to create asealed second interior volume 410.

At least two skives 424 and 426 may be defined by the inner tube 422 andemployed to allow the working fluid to exit into the second interiorvolume 410 and to exhaust the same from the second interior volume. Asshown in the figure, the skive 424 is in fluid communication with thelumen 420 and the skive 426 is in fluid communication with the lumen418. Here, “fluid communication” refers to a relationship between twovessels where a fluid pressure may cause a net amount of fluid to flowfrom one vessel to the other.

The skives may be formed by known techniques. A suitable size for theskives may be from about 50 mils to 125 mils.

At least one pore 415 may be provided within the outer balloon 404. Inthis way, a portion of the fluid within the first interior volume 406may leak to the exterior of the outer balloon 404, contacting the tissueand providing enhanced heat transfer, due to conduction, between thefluid and the tissue to be treated.

The method of making a porous or microporous balloon is known, andeither may be employed in this application. Such balloons arealternatively known as “weeping” balloons. In such balloons, pore sizescan be controlled at least to the micron range. The pore size determinesthe rate of release of the fluid. A conflicting requirement is that theballoon must be inflated and deployed, this requirement having theeffect that the balloon must be strong and at least about 1-2atmospheres of pressure must be maintained in the balloon.

These requirements can still be met in the present porous or microporousballoon as the fluid leakage is generally small, especially as the timeof therapy may be on the order of 1-2 consecutive treatments at 60-90seconds each. Over such a period of time, it may be expected that only1-2 ml may be leaked.

In alternative embodiments, the pores can be designed to be placed in aband, so as to only leak at about where the circumferential region oftissue is located. Alternatively, the pores can be placed in a helix,spiral, e.g., relative to an axis 401 of the catheter, or other suchshape as dictated by the demands of the user. Only one pore may be usedin applications where only a minimum of enhanced conductivity isrequired.

In a treatment-of-restenosis method of use, the guide catheter 402 maybe inserted into an affected artery or vein such that the distal tip ofthe guide catheter is just proximal to an affected area such as acalcified area or lesion.

The catheter 400 may then be inserted over the guide wire via the lumen416 and through the guide catheter 402. In general, both a guide wireand a guide catheter are not strictly necessary—one or the other mayoften suffice. During insertion, the dual balloon 434 may be uninflatedto maintain a minimum profile. In fact, a slight vacuum may be drawn tofurther decrease the size of the dual balloon 434 so long as thestructural integrity of the dual balloon 434 is not thereby compromised.

The fine positioning step by way of the radio opaque marker bands 412and as described above in connection with FIG. 1 may then occur. Onceplaced, a biocompatible heat transfer fluid, which may also containcontrast media, may be infused into the first interior volume 406through the inlet 428. This fluid then begins to leak via pores 415,flowing between the balloon and the tissue to be treated and enhancingthe conductive heat transfer between the two.

The biocompatible cooling fluid may then be circulated through thesupply lumen 420 and the return lumen 418. As noted above in connectionwith FIG. 1, the fluid exits the supply lumen 420 through the skive 424and returns to the chiller through the skive 426 and via the returnlumen 418. It is understood again that the respective skive functionsmay also be reversed without departing from the scope and spirit of theinvention.

Upon completion of the therapy, the circulation of the biocompatiblecooling fluid may cease. The remaining heat transfer fluid within thefirst interior volume 406 may be withdrawn though the inlet 428. Theballoons 404 and 408 may be collapsed by pulling a soft vacuum throughany or all of the lumens 424, 426, and 428. Following collapse, thecatheter 400 may be withdrawn from the treatment site and from thepatient through the guide catheter 402.

Referring to FIG. 9, an alternative embodiment of a catheter which maybe employed in PV ablation is detailed. In this figure, a dual balloonsystem 501 is shown which is similar to the embodiment of FIG. 3.

However, the balloons are not one within the other as in FIG. 1. In thisembodiment, warm balloon 502 may be used to anchor the system 501against movements, while cold balloon 504 may be employed to cryo-ablatea circumferential lesion at the point where a pulmonary vein 506 entersthe left atrium 508.

Within the cold balloon 504, a working fluid may be introduced via anoutlet port 508 and may be retrieved via an inlet port 510. Ports 508and 510 may be skived in known fashion into the catheter shaft lumenswhose design is exemplified below. The cold balloon 504 may be a porousor microporous balloon, having pores as indicated in FIG. 9 by pores515.

As in the embodiment of FIG. 3 noted above, the warm balloon 502 servesto anchor the system 501 in the pulmonary vein and left atrium. The warmballoon 502 also serves to stop blood, which is traveling in thedirection indicated by arrow 512, from freezing upon contact with thecold balloon 504. In this way, the warm balloon 502 acts as an insulatorto cold balloon 504.

As the warm balloon 502 does not require convective heat transfer via acirculating working fluid, it may be served by only one skived port, orby two ports, such as an inlet port 514 and an outlet port 516, as shownin FIG. 9. In some embodiments, a separate lumen or lumens may be usedto fill the warm balloon. In an alternative embodiment, a valvemechanism may be used to fill the warm balloon using fluid from the coldballoon. In the case where only one port is used to fill the warmballoon, draining the same requires a slight vacuum or negative pressureto be placed on the lumen servicing the inlet/outlet port.

Typical pressures within the warm balloon may be as above. Typicalpressures within the porous cold balloon may be about 1-2 atm, forexample about 1.5 atm. An appropriate cryogenic fluid may be Galdenfluid, e.g., HT-55, or others with similar properties. The volume offluid required to fill the cold balloon may vary, but may be about 4-8cc. The cold balloon may be about 2 to 2½ cm long, and have a diameterof 1 to 4 cm.

A porous or microporous balloon may also be employed in application inwhich the above or similar balloons are employed to treat restenosis.For example, following an angioplasty procedure, the angioplasty balloonmay be removed while the guidewire left in place. As withtreatment-of-atrial fibrillation procedure, the balloon may be deliveredup to the location of treatment via the guidewire, and operated for aminute, or other appropriate time as determined by, e.g., the physician.In the restenosis application, the outer diameter of the catheter wouldtypically be less than about 6 French, as the same would requirecompatibility with existing coronary angioplasty hardware, such as a 9French guide catheter.

The invention has been described above with respect to particularembodiments. It will be clear to one of skill in the art that numerousvariations may be made from the above embodiments with departing fromthe spirit and scope of the invention. For example, the invention may becombined with stent therapies or other such procedures. The dual balloondisclosed may be used after angioplasty or may be an angioplasty balloonitself. Furthermore, while the invention has occasionally been termedherein a “cryoplasty catheter”, such a term is for identificationpurposes only and should not be viewed as limiting of the invention.Fluids that may be used as heat transfer fluids includeperfluorocarbon-based liquids, i.e., halogenated hydrocarbons with anether bond, such as FC 72. Other materials that may be used includeCFCs, Freon®, or chemicals that when placed together cause anendothermic reaction. Preferably, low viscosity materials are used asthese result generally in a lessened pressure drop. The balloons may bemade, e.g., of Pebax, PET/PEN, PE, PA 11/12, PU, or other suchmaterials. Either or both of the dual balloons may be doped to improvetheir thermal conductivities. The shafts of various tubes mentioned,such as inner tube 122, may be made of Pebax, PBT, PI/PEI, PU, PA 11/12,SI, or other such materials. The precise shapes and dimensions of theinner and outer lumens, while indicated in, e.g., FIGS. 1B, 1C, and 2B,may vary. The lumen design shown in FIGS. 1B-1C may be employed in thecatheter of FIG. 2A and vice-versa. Either a single cold balloon system,or a dual balloon system, may be employed in either or both of thementioned applications of treating restenosis or atrial fibrillation, orother such maladies. Embodiments of the invention may be employed in thefield of cold mapping, where a circle of tissue is cooled to see if theaffected part has been reached. If the affected tissue is that which isbeing cooled, a more vigorous cooling may be instituted. Othervariations will be clear to one of skill in the art, thus the inventionis limited only by the claims appended hereto.

1. A catheter system to treat restenosis or atrial fibrillation,comprising: a catheter shaft; a warm balloon disposed on the cathetershaft, said warm balloon fluidically coupled to at least one lumen forinflating and deflating the warm balloon; and a cold balloon disposed onthe catheter shaft, said cold balloon having at least one pore formedtherein, and fluidically coupled to two lumens for circulating a coldworking fluid to and from the cold balloon, such tat said cold balloonis located adjacent but proximal to said warm balloon, wherein said warmballoon is structured and configured to anchor in a pulmonary vein, andwherein said cold balloon is structured and configured to be disposedpartially in the pulmonary vein and partially in the left atrium.
 2. Thesystem of claim 1, wherein said warm balloon is made of silicone tubing.3. The system of claim 2, wherein said warm balloon is secured by heatshrink tubing.
 4. The system of claim 2, wherein said warm balloon issecured by an adhesive.
 5. The system of claim 2, wherein said warmballoon is secured by bands.
 6. The system of claim 5, wherein saidbands are metal.
 7. The system of claim 1, wherein said working fluid isa perfluorocarbon.
 8. The system of claim 1, wherein said cold balloonhas a length of between about 1 to 2½ cm and a diameter of between about1 to 2½ cm.
 9. The system of claim 1, further comprising at least onemarker band disposed within one or both of the cold balloon and the warmballoon.
 10. The system of claim 1, further comprising a set of mappingelectrodes disposed distal of the warm balloon.
 11. The system of claim1, further comprising an insulation sleeve disposed around the cathetershaft.
 12. The system of claim 11, wherein the insulation sleeve isformed of a foamed extrusion.
 13. The system of claim 1, furthercomprising a silicone sleeve disposed circumferentially about thecatheter shaft adjacent a point at which at least one of the cold orwarm balloons attaches to the catheter shaft.
 14. The system of claim 1,further comprising a gear pump, and wherein the cold working fluid iscirculated by said gear pump.